Failure Analysis System Procedure. Submersible Vertical Pumps SVI. Lowara. 1) Electric pump applications

Transcription

1 Failure Analysis System Procedure Submersible Vertical Pumps SVI 1) Electric pump applications Pumping of cooling liquids, lubricating and condensate Machine tool, welding machine, motor test-bed Cooling systems Washing systems Booster Fire fighting systems 2) Critical items of application 2.1) Electrical supply In running condition, max variation of supply voltage: ± 10%. - a too high voltage generates overheating and overload; - a too low voltage generates starting problems. Max frequency of start: 20 start/h for power until 5.5 kw; 15 start/h for power until 15 kw; 12 start/h for power greater than 15 kw - an excessive number of starting generates overheating and overload of motor. 1 Date edition: 12/2006

2 2.2) Liquid Pumps made in standard configuration (ceramic/coal/fpm) must pump clean liquids with the following limits of temperature: - SVI pump, "S" and "N" versions: -10 C, +90 C, - SVI pump, "E" version: -10 C, +60 C. In case of particular applications and range of temperature more extended, pumps must be configurated with attention. Main configurations realized, based on the type of application, are wrote in the following table: Application Tools lubrication Filtration of liquid of machine tool Advised seal (*) Standard seal Ceramics/Coal/FPM Widia/Widia/FPM Note In presence of chips Widia/Widia/FPM or Silicon carbide/silicon carbide/fpm Liquid witch contain chips Deionized water Demineralized water Swimming pools Washing of systems for the food industry Silicon carbide/special coal/epdm ofpm Silicon carbide/special coal/epdm o FPM Widia/Special coal/epdm Widia/Special coal/epdm Suitable for waters witch have just undergone by process of direct or reverse osmosis Waters witch contain chlorides with variable concentrations Mixture of water and hard caustic: max conc. 20%, Tmax 80 C. Generics washing systems Widia/Special coal/epdm Products to alkaline base with Ph between 8 and 10. For greater Ph it is advised Widia/Silicon carbide/epdm Refrigeration systems Widia/Special coel/epdm or Widia/Silicon carbide/epdm Mixture of water and glycol with concentration from 10% to 100% and temperature from -55 C to +40 C Transfer/pumping of generic chemical products It is advised contact the sale net Large tipology of acids (*) Rotating part/fixed part/o-ring Pumping of diesel oil or others inflammable liquids is concurred only with use of special version pumps and equipped with ATEX motor. Pumping of abrasive liquids is forbidden because of rapid wear of hydraulic part. Pumping of liquid containing filaments is forbidden because if obstruction of filter. If it is pumped a liquid with a viscosity greater than water viscosity, it is necessary performe a oversizing of the motor to avoid its overheating. Pumping of sea water, brackishwater or with a great concentration of chlorine is not adviced because of priming of corrosive phenomena in hydraulic part. 2 Date edition: 12/2006

3 2.3) Installation Max environement temperature: 40 C. Min level of liquid in suction: 25 mm for SVI versions; 100 mm for SVI versions; - if the level is lower than fixed values, pump work in dry conditions and it generates a rapid wear of hydraulic part; - it is advised to check periodically the liquid level and keeping it in the fixed limits. Pumping of liquid containing solid parts, generates a rapid obstruction of filter, moreover the solid particles can insert between shaft and bush, witch can break off itself; for this reasons, it is advised installation of prefilter. Installation of pump in environement with a great humidity causes damaging of motor bearings. After pump installation, it is advised to wait some minutes before the start to get time to water to penetrate in the pump body. In starting condition, it is necessary take the delivery outlet open to let out the air from the pump: - if there is air in the pump, it can be priming problems and it can damage the hydraulic part. Pump must not work with the delivery outlet closed for a time longer than 4-5 min. Otherwise, it generates overheating of liquid and damages of mechanical seal. Pump must never operates without water to avoid damages of mechanical seal and hydraulic part. If the pump is installed in a tank, the reinstatement of pumped liquid must be performed avoiding that the air boubbles goes near the suction inlet and they be pumped. Pumping of liquid containing gas generates wear of hydraulic part and increasing of pump noise. It is necessary guarantee a correct air flow for motor cooling. It is necessary the ventilation grid is not partially or totally obstructed; otherwise it generates overheating and overload of motor. It is necessary insert a non return valve inside of delivery for protect the pump from water hammer and reverse rotation. Normally, the pump is installed with vertical axis; it can be also installed with horizontal axis, except for SVI versions with more than 5 stages at 50 Hz and SVI versions with more than 4 stages at 60 Hz. In case of installation with horizontal axis, it is advised the presence of hole on the pump body near the upper impeller to let out the air boubbles from pump body. If it should remove an impeller to reduces a pump head, it is advised to remove the upper impeller to guarantee a respect of minimum level of liquid. If it is pumped a slimy liquids, it is advised to rinse the pump after its use to avoid the damaging of bushes. 1~ motors have an internal motor protection but they cannot operate without a operator supervision or insertion of additional protections inside of control board. 3~ motors must be protected with a circuit breaker installed by a Customer (it is adviced use of Lowara control board). It is recommended installation of high sensibility differential switch (I n 0.03 A) inside of control board, to protect the people from possible electric contact with live parts. 3 Date edition: 12/2006

4 2.4) Operation with inverter Operation with inverter positioned inside of the control board not present particular limits (see the inverter handbook). 3) Equipments and tools required and tools required Megaohmeter Vdc; 4) Inspection of defected product 4.1) Preliminary information On receiving of defective product, requirements from Customer: purchase date (if possible, confirmed by bill or sale slip); installation date; conditions of installation. 4.2) External visual inspection Check the external condition of product, in a particular manner check on the surface of pump body the presence of weld or fusion defects and integrity of aluminum motor casing. 4.3) Preliminary inspections Data in plate: - type of product and code; - series number; - manufacturing date; Based on type of application witch is subject the pump, check if the configuration is right or wrong (see the table in 2.2). Condition of capacitor (1~ motor). 4.4) Electrical resistence of windings Measure electrical resistance of windings to find possible damages (interruptions/burnings). 4.5) Measure of insulation resistance Performed in accordance with european standard EN (500 Vdc between conductors and ground). Test is passed if insulation resistance is 10 MΩ. 5) Disassembly and analysis N.W. The pictures refers to the pump SVI 2 (with join). Remove the protection grid of coupling join and check the two elements of join are installed correctly (in balanced manner). Check with a thickness gauge the position of hydraulic pack: a wrong position generates a sliding of impellers on the diffusers. Remove the coupling joint. 4 Date edition: 12/2006

5 Remove the fixing screws witch connects the delivery outlet to the motor, so separate the motor to the pump. Extract the screws and remove the filter: - check the presence of foreign matters. Unscrew the nuts and remove the suction bottom. Extract the sleeve and the first hydraulic box, so unscrew the fixing nut. Extract one by one all stages compounded of diffuser, impeller and spacer: - check wear of impeller and presence of defects in the welds. 5 Date edition: 12/2006

6 Extract the pump shaft and check: - integrity; - condition of surface of the mobile part of mechanical seal. Extract from the adaptor the fixed part of mechanical seal and check the condition of its surface. Remove the protection grid and the fan of motor. Remove the motor cover, separate the rotor to motor casing and check the condition of bearings. Performe an heads visual analysis for finding possible problems with following cases: a) all motors: - one or more winding coils burnt ----> shorted coil; b) 1~ motor: - run winding OK and start winding KO ----> capacitor defected; - run winding KO and start winding OK ----> motor could not start; - both windings faulty ----> overload; c) 3~ motor: - 1 phase fine and 2 phases burnt ----> powered with only 2 phases; - all phases burnt ----> overload. 6 Date edition: 12/2006

7 6) Check list Type of problem Does not delivery water Low performance Does not starts Noisy Grounded motor Excessive power input Runs slowly Further: Pump data Type: Code: Series number: Installation date: Manufacturing date: Liquid pumped: Temperature: Remarks: SVI pumps failure causes required for claim opening Where What Why 100 Electric motor 100 Flooded/full of water 110 holes of drain condensate, obstructed/closed 111 Pinched gasket screws 100 Electric motor 101 Excessive power input / 102 Motor shaft locket overheating / burnt 104 Wrong internal electrical connections 107 Bursted / unconnected capacitor 108 Short circuit for contact with mobile parts 109 Short circuit between coils/windings 114 Hydraulic rotating part locked 115 Presence of external matters between windings 121 Inadequate power supply 113 Inadequate size of motor 116 Inadequate cooling 100 Electric motor 102 Runs slowly / does not starts 107 Bursted / unconnected capacitor 117 Defected/wrong rotor 118 Not operating level sensors 119 Water full level sensors 121 Inadequate power supply 113 Inadequate size of motor 100 Electric motor 103 Does not stops 105 Defected/not operating electrical/electronic components 118 Not operating level sensors 101 Motor shaft 104 Noisy / locked / vibrate (ok windings) 102 Locked motor shaft 114 Hydraulic rotating part locked 7 Date edition: 12/2006

8 101 Motor shaft 101 Motor shaft 401 Broken/cracked 200 Control device 300 Total hydraulic 300 Low performance 300 Total hydraulic 403 Pump sleeve 400 Leak 404 OR/Mechanical seal 408 Pump shaft/joint 600 Product 102 Shaft / toothing jut 200 Not operate 104 Noisy / locked / vibrate 400 Leak 401 Broken/cracked 600 Wrong rating plate packing 601 Wrong product document 602 Not acknowledgment of warranty 105 Defected/not operating electrical/electronic components 200 Lack of technical / commercial information 118 Not operating level sensors 119 Water full level sensors 121 Inadequate power supply 300 Wrong rating plate/packing 114 Hydraulic rotating part locked 200 Lack of technical / commercial information 600 Out of legal warranty period 601 Product tampering 8 Date edition: 12/2006

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10 8) Faq Problem founded Pump does not start Possible causes of the problem Power supply problems: no power; unconnected or damaged cable; supply voltage too low; Hydraulic locked. Fuses burnt. Circuit breaker tripped or not calibrated. Capacitor too small or damaged (1~ motor). 2 phases powered (3~ motor). Motor is burnt because of insulation defected, overheating or overload (unsuitable liquid) Pump does not delivery water Non return valve clogged Filter obstructed. Water level too low Pump run in the opposite way Pump operates in cavitation Low performance Filter partially obstructed Pump run in the opposite way Clogged non return valve Unsuitable liquid (density or specific weight >1) Wear of hydraulic part System leaks Noisy Runs slowly Pump operates in cavitation condition Motor bearings damaged cause by condensate Presence of foreign matters Run and start windings exchanged on control panel (1~ motor) Wrong windings connections inside the motor (3~ motor) Grounded motor Excessive power input Generation of condensate inside the motor Insulation defected Uncorrect voltage Windings defected Motor supplied with 2 phases (3~ motor) Unsuitable liquid Defected pump Defected bearings Too high frequency of startings 10 Date edition: 12/2006

11 Hydraulic locked Overheating/overload Unsuitable liquid Presence of foreign matters inside of pump Tolerance of tooling beyond the limits O-ring out of seat Too high liquid temperature Too high frequency of startings Wrong supply voltage Defected pump Thrust bearings damaged/seized Lack of adequate protection inside of control board (for motors without internal protection, see 2,3) Lack of ventilation of the motor Too high environment temperature 11 Date edition: 12/2006

12 7) Failure tree (SVI pumps) DOES NOT STARTS LOW PERFORMANCE NOISY EXCESSIVE POWER INPUT GROUNDED MOTOR No power Delivery outlet partially clogged Pump operates in cavitation condition Uncorrect voltage Condensate inside of motor Cable unconnected or damaged Supply voltage too low Fuses burnt Pump run in the opposite way Clogged non return valve Unsuitable liquid Motor bearings damaged / weared Presence of foreign matters inside of pump Windings defected Motor supplied with 2 phases instead of 3 (3~ Unsuitable liquid Insulation defected Presence of foreign matters RUNS SLOWLY 8 Date edition: 12/2006 Circuit breaker tripped/not calibrated Too small or damaged capacitor (1~ motor) 2 phases supplied (3~) Hydraulic locked Faulty stator Overheating / overload Insulation defect Hydraulic wear System leaks PUMP DOES NOT DELIVERY WATER Clogged non return valve Liquid level too low Delivery outlet obstructed Pump not primed Filter obstructed Overload Defected pump Damaged bearings Too high frequency of starting Run and start windings exchanged on control Wrong windings connections (3~) LEAKS OF HYDRAULIC PART Mechan. seal damaged O-Ring damaged Weld or fusion defected Lowara